Screen PPI Calculator
Calculate a screen's pixel density (PPI/DPI) from its resolution and diagonal size, plus dot pitch and total megapixels. Great for choosing monitors and phones. Private.
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Work out a screen’s pixel density
Pixel density, measured in pixels per inch, is what actually determines how sharp a screen looks, and yet it is almost never printed on the box or the spec sheet. This calculator computes PPI from a screen’s pixel resolution and its diagonal size, so you can meaningfully compare how crisp two different displays really are rather than being misled by resolution alone. It turns two numbers you can find into the one number that reflects sharpness.
Why resolution alone is misleading
A high resolution figure means surprisingly little on its own without also knowing the physical screen size, because the exact same pixel count looks razor-sharp when packed onto a small phone and noticeably coarse when spread across a large monitor, simply because the pixels cover a very different area. PPI combines resolution and physical size into a single number that genuinely reflects sharpness, which is why it, and not raw resolution, tells you how a display will actually look. The calculation uses the diagonal and pixel dimensions via the Pythagorean theorem.
Compare displays fairly
It runs entirely in your browser, so nothing you enter is uploaded and the generated code is yours to paste straight into a project. Because it works client-side, you can iterate freely, regenerating as often as you like without a round trip to any server.
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Frequently Asked Questions
What is PPI?
Pixels per inch: how densely packed a screen’s pixels are, which determines how sharp it looks. Higher PPI means a crisper image.
Why is resolution alone misleading?
Because the same pixel count is sharp on a small screen and coarse on a large one. PPI combines resolution and physical size to reflect actual sharpness.
How is PPI calculated?
From the pixel resolution and the diagonal size: the pixel diagonal, found with the Pythagorean theorem, divided by the physical diagonal in inches.
What PPI looks sharp?
Phones reach several hundred PPI and look razor-sharp; desktop monitors are often lower. The right target depends on viewing distance.
Is my input uploaded?
No. The calculation runs entirely in your browser.
Privacy & Security
All processing happens locally in your browser — nothing is uploaded.
How to Use
Enter the horizontal and vertical resolution and the diagonal size in inches.
Disclaimer: This tool is provided "as is" without warranty of any kind. Results are for educational and utility purposes.
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